1. Field of the Invention
This invention relates to a face hobbing cutter. More particularly, this invention relates to a face hobbing cutter including a plurality of wedge clamping assemblies for securing cutting blades.
2. Description of the Related Art
Face hobbing comprises cutting blades arranged about a cutter, not in line with each other, but in groups, usually pairs comprising an inner cutting blade and an outer cutting blade. Unlike most face milling processes, in which all cutting blades pass through the tooth slot during its formation, face hobbing comprises each successive group of cutting blades passing through respective successive tooth slot with each blade in the group forming a cut completely along the longitudinal portion of the tooth slot. The cutter and the workpiece rotate in a timed relationship with each other thereby allowing continual indexing of the workpiece and continual formation of each tooth slot of the gear. A single pair of cutting blades produces a tooth slot.
In hobbing processes to produce gears, it is known to utilize cutting tools wherein one or more cutting blades are positioned in and project from cutter head assemblies. See, for example, U.S. Pat. No. 4,621,954 to Kitchen et al. or U.S. Pat. No. 5,890,846 to Clark et al., incorporated herein by reference. The cutting blades are typically secured in position in a cutter head by one or more clamping screws. The clamping screws may be in direct contact with the cutting blades such as shown in U.S. Pat. No. 4,268,194 to Bloink et al. or U.S. Pat. No. 4,530,623 to Kotthaus, incorporated herein by reference. In other instances, clamping screws may contact a clamp block which in turn contacts a cutting blade as can be seen, for example, in the previously mentioned U.S. Pat. No. 4,621,954 or U.S. Pat. No. 5,890,846. With the clamp block arrangement, clamping forces can be spread out along the blade-clamp block interface instead of the point contact that occurs with direct contact between the clamp screw and cutting blade.
The present invention is specifically concerned with improvements in face hobbing cutters designed for use in gear cutting machinery capable of generating tooth profiles for spiral, bevel and hypoid gears. In applications of this type, dimensional relationships of the cutting blades are extremely critical and must be maintained to close tolerances in order to obtain a desired tooth profile for each tooth and slot of the final gear product. One of the relationships which must be carefully maintained is the angle and position of the cutting face (or chip face) of each cutting blade relative to the cutter head assembly in which it is carried and to the workpiece which is being cut. Although cutting blades of the type shown in U.S. Pat. No. 2,186,417 require no resharpening of their front faces, it is believed that all prior efforts in designing and resharpening cutting tools for gear cutting applications have required a careful resharpening of the cutting face each time the cutting tool is resharpened for further usage in a cutter head assembly (see, for example, U.S. Pat. No. 3,487,592). This requirement of past designs adds to the cost of use of a particular tool.
In contrast to prior art methods, the present invention provides for a cutter head assembly which permits use of individual cutting blades which can be easily replaced as necessary and adjusted in such a manner that all of the critical relationships required for gear cutting applications are maintained. Thus, a cutter head assembly is specifically designed in accordance with the present invention to receive a cutting blade which can be replaced as desired and easily adjusted to obtain optimum cutting performance of the face hobbing cutter.
Briefly, according to this invention, there is provided a face hobbing cutter. The face hobbing cutter includes a cutter body having a top surface and a bottom surface and a side surface extending between the top surface and the bottom surface. A plurality of slots are formed within the cutter body extending from the top surface inward into the cutter body. The slots are adapted to receive cutting blades; wherein each cutting blade is fixed in position in the respective slot by a wedge clamping assembly. The wedge clamping assembly includes a wedge block and a wedge screw for operatively securing the wedge block within the respective slot. The wedge block includes a locking surface for engaging a side of the cutting blade. The face hobbing cutter further includes an adjustable stop. The adjustable stop is in communication with the slot to support the cutting blade at the desired height from the top surface of the face hobbing cutter.